Ptolemy devotes a column or two of his _Almagest_[22] (to use the familiar Arabic name for his _Syntaxis Mathematica_) to the refutation of the heliocentric theory, thereby preserving it for later ages to ponder on and for a Copernicus to develop. He admits at the outset that such a theory is only tenable for the stars and their phenomena, and he gives at least three reasons why it is ridiculous. If the earth were not at the center, the observed facts of the seasons and of day and night would be disturbed and even upset. If the earth moves, its vastly greater mass would gain in speed upon other bodies, and soon animals and other lighter bodies would be left behind unsupported in the air--a notion "ridiculous to the last degree," as he comments, "even to imagine it." Lastly, if it moves, it would have such tremendous velocity that stones or arrows shot straight up in the air must fall to the ground east of their starting point,--a "laughable supposition" indeed to Ptolemy. [Footnote 22: Ptolemy: _Almagest_, Lib. I, c. 7, (1, 21-25). Translated in Appendix B.] This book became the great text of the Middle Ages; its author's name was given to the geocentric theory it maintained. Astronomy for a thousand years was valuable only to determine the time of Easter and other festivals of the Church, and to serve as a basis for astrology for the mystery-loving people of Europe. To the Arabians in Syria and in Spain belongs the credit of preserving for Europe during this long period the astronomical works of the Greeks, to which they added their own valuable observations of the heavens--valuable because made with greater skill and better instruments,[23] and because with these observations later scientists could illustrate the permanence or the variability of important elements. They also discovered the so-called "trepidation" or apparent shifting of the fixed stars to explain which they added another sphere to Ptolemy's eight. Early in the sixth century Uranus translated Aristotle's works into Syrian, and this later was translated into Arabic.[24] Albategnius[25] (c. 850-829 [Transcriber's Note: 929] A.D.), the Arabian prince who was the greatest of all their astronomers, made his observations from Aracte and Damascus, checking up and in some cases amending Ptolemy's results.[26] [Footnote 23: Whewell: I, 239.] [Footnote 24: Whewell: I, 294.] [Footnote 25: Berry: 79.] [Footnote 26: His book _De Motu Stellarum_, translated into Latin by Plato Tiburtinus (fl. 1116) was published at Nuremberg (1557) by Melancthon with annotations by Regiomontanus. _Ency. Brit._ 11th. Edit.]